Obviously topical at the moment, but the current situation did get me thinking about this. I would guess diesel quantities could be higher than petrol as it's less dangerous, but I can't find any references to how much you can store and what you can store it in. I have a 20L jerry can, but they cannot be used now for petrol, but what about diesel? Anyone got an authorative link?

Is this possible? The rubber cap at the back came off and moisture's got inside leading to fogging. I can dry that out, but there are some steaks (water marks) on the inside of the front plastic 'lens'. Can the 'lens' be removed and replaced safely?

Yeah - main difference with a diesel *should* be better fuel economy than petrol when in equivalent stop start/small throttle openings. One reason why they've remained popular for delivery vans, despite the higher fuel price.

I find economy (according to the avg mpg on the dash) gets a LOT better when I'm stuck in slow speed traffic on the motorway, even if it's a bit stop-start, and best if it just stays moving and I don't have to brake too much. In that situation I'm forced to 65mph or less typically. Also get in the habit of using the 'slow' lane so long a people are making reasonable progress. If you do the maths, it won't actually increase your journey time as much as you think it will - and five or ten minutes here or there usually doesn't get noticed too much on a longer trip. From http://en.wikipedia.org/wiki/Fuel_economy_in_automobiles "The power to overcome air resistance increases roughly with the cube of the speed, and thus the energy required per unit distance is roughly proportional to the square of speed. Because air resistance increases so rapidly with speed, above about 30 mph (48 km/h), it becomes a dominant limiting factor. Driving at 45 rather than 65 mph (72 rather than 105 km/h) requires about one-third the power to overcome wind resistance, or about one-half the energy per unit distance, and much greater fuel economy can be achieved. Increasing speed to 90 mph (145 km/h) from 65 mph (105 km/h) increases the power requirement by 2.6 times, the energy per unit distance by 1.9 times, and decreases fuel economy. In real world vehicles the change in fuel economy is less than the values quoted above due to complicating factors." Basically, drive a BIT slower and save a LOT of fuel. Cruise controls aren't the best way of saving fuel either, as popular wisdom is that it's more efficient to let the car slow down when climbing hills... (though maybe it's just better just because you're going more slowly at a more efficient throttle opening)

I think a lot is down to driving style and how you use the available power. Also Diesels are supposed to be relatively more efficient at narrow throttle openings compared with petrol, so blasting down the motorway at 80 (and overcoming all the wind resistance at that speed) isn't going to get you amazing economy and possibly not much better than a petrol equivalent. Increasing speed a little increases wind resistance disproportionately. I don't think the revs has much to do with - think of gas guzzling slow revving American V8's! Low revs just means it's not a buzz box. For what it's worth I had a 1.6 petrol Focus as a loan car for a day. Amazing how gutless it felt and how I seemed to have to rev it all the time. Gotta love diesels in this respect. Just have to be going fast enough not to hear/feel the diesel's engine's 'unrefined' noise! I've done 36000 in my 1.6 tdci and have averaged about 57mpg. I drive 'gently'.

Is there a trade-off using these kind of tuning boxes (other than their initial cost)? Seems odd that manufacturers wouldn't do this as standard to get class leading performance/enconomy... Why wouldn't they?

Bought a pre-registered Focus 1.6 tdci 110 on a 57 plate from 'new'. Lots of talk with the dealer about DPFs but at my predicted mileage at the time decided to go with it anyway. Just had a 37.5K/3yr service where the DPF fluid is supposed to be topped up. Car siad it needed the service at 35.5K so I had it don then. Anyway, turns out it doesn't have a DPF :-) Apparently at that time a few engine variants didn't get one. Maybe then I have the last of a few like that? :-) Maybe make the car worth a little more when I come to sell it...

Drove through a big fr***ing pothole this morn. Deflated a front tyre and bent an (alloy) wheel rim. £170 odd for a new wheel (cheap compared to some). Then Ford parts guy said try Blackboots (tyre place) locally. They'll say if it can be "repaired". They said: 1. For £40+VAT we can try and press it out, refit the tyre (which was ok), & rebalance. Should the alloy show any signs of cracking they could then get 2. the crack cut out and repaired ("welded") for a further £40+VAT (I didn't like the sound of that) Decided to risk (1). Went back 2 hours later, and I could barely tell there had ever been a problem. Just the paint on the wheel marked (fortunately on the inside rim) when they had obviously gripped the wheel in a press. Course, can't tell what internal stresses can't be seen, but it did look bent rather than a plastic deformation. Anyone want a lift anywhere in my car ;-) ? Need to get alignment/geometry checked now after a bump like that... more expense... I was quite impressed though - so thought I'd share... http://www.blackboots.co.uk/alloywheelrepairs.php